The present invention relates to a machining solution intended for use in electrospark machining.
A so-called "ordinary electrospark machining method" using a mold electrode and a wire type electrospark machining method employing a wire electrode are well known in the art. In each of these methods, a machining electrode is confronted with a workpiece in a machining solution with a gap between the electrode and workpiece and the workpiece is machined by sparks produced in the gap.
During the electrospark machining operation, machining solution is abruptly vaporized by columns of sparks to produce a high pressure which dislodges molten parts of the workpiece. The machining solution also serves to cool molten fine metal particles which have been scattered from the workpiece thereby to remove machining chips, decomposed carbon particles, and other unwanted debris from the machining gap.
In general, the machining solution used with the wire type electrospark machining method is water. Therefore, there is little danger of fire caused by the machining solution. On the other hand, an inflammable oil such as mineral oil, which is a good insulator, is generally employed as the machining solution used with the ordinary electrospark machining method because water greatly reduces the machining rate. Unfortunately, if the level of the inflammable machining solution in the machining bath decreases significantly during an electrospark machining operation, the solution may be ignited by the sparks resulting in a fire. Thus, the ordinary electrospark machining method is disadvantageous in that it is necessary to provide a way of preventing the inflammable machining solution from igniting.
However, since a inflammable machining solution must be used as a practical matter, the ordinary electrospark machining method suffers from a drawback in that, even if a way is provided for preventing ignition of the machining solution, it is impossible to assure that unmanned operation is absolutely safe for long periods. Furthermore, the inflammable mineral oil itself involves a problem in that it is malodorous, somewhat poisonous and presents a sanitation problem in that it tends to stick to the hands of the operator.
In order to prevent fires, a nonflammable oil such as a silicon oil, fluorinated oil or chlorinated oil may be employed as the machining oil. However, silicon oil and fluorinated oil are considerably expensive and chlorinated oil is poisonous.